Constraining a Model of Turbulent Coronal Heating for AU Microscopii with X-Ray, Radio, and Millimeter Observations

Abstract

Many low-mass pre-main-sequence stars exhibit strong magnetic activity and coronal X-ray emission. Even after the primordial accretion disk has been cleared out, the star's high-energy radiation continues to affect the formation and evolution of dust, planetesimals, and large planets. Young stars with debris disks are thus ideal environments for studying the earliest stages of non-accretion-driven coronae. In this paper we simulate the corona of AU Mic, a nearby active M dwarf with an edge-on debris disk. We apply a self-consistent model of coronal loop heating that was derived from numerical simulations of solar field-line tangling and magnetohydrodynamic turbulence. We also synthesize the modeled star's X-ray luminosity and thermal radio/millimeter continuum emission. A realistic set of parameter choices for AU Mic produces simulated observations that agree with all existing measurements and upper limits. This coronal model thus represents an alternative explanation for a recently discovered ALMA central emission peak that was suggested to be the result of an inner "asteroid belt" within 3 AU of the star. However, it is also possible that the central 1.3 mm peak is caused by a combination of active coronal emission and a bright inner source of dusty debris. Additional observations of this source's spatial extent and spectral energy distribution at millimeter and radio wavelengths will better constrain the relative contributions of the proposed mechanisms.

Accepted for publication in the Astrophysical Journal. 8 pages (emulateapj style), 4 figures

References in corpus (12)

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• Magnetic Cycles in a Convective Dynamo Simulation of a Young Solar-type Star
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• Millimeter Emission Structure in the first ALMA Image of the AU Mic Debris Disk
• What controls the magnetic geometry of M dwarfs?
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• Simulations of turbulent convection in rotating young solar-like stars: Differential rotation and meridional circulation
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Cited by in corpus (22)

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• The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical Structure
• Collisional modelling of the AU Microscopii debris disc
• The AU Mic Debris Disk: far-infrared and submillimeter resolved imaging
• AU Microscopii in the FUV: Observations in Quiescence, During Flares, and Implications for AU Mic b and c
• Simulating the Space Weather in the AU Mic System: Stellar Winds and Extreme Coronal Mass Ejections
• Constraining the Radiation and Plasma Environment of the Kepler Circumbinary Habitable Zone Planets
• Resolved Multifrequency Radio Observations of GG Tau
• Searching for flaring star-planet interactions in AU Mic TESS observations
• Magnetic Field of the Active Planet-hosting M Dwarf AU Mic
• Observability of Debris Discs around M-stars
• Resolving Structure in the Debris Disk around HD 206893 with ALMA
• An ATCA survey of debris disks at 7 millimeters
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) II. The radial structure of debris discs
• Time-Dependent Turbulent Heating of Open Flux Tubes in the Chromosphere, Corona, and Solar Wind
• MESAS: Measuring the Emission of Stellar Atmospheres at Submm/mm wavelengths
• The big sibling of AU Mic: a cold dust-rich debris disk around CP-72 2713 in the $\beta$ Pic moving group
• Optical Coronagraphic Spectroscopy of AU Mic: Evidence of Time Variable Colors?
• The MESAS Project: Long wavelength follow-up observations of Sirius A
• Non-Linear Convergence of Solar-like Stars Chromospheres using Millimeter, Sub-millimeter, and Infrared Observations
• The Proxima Centauri Campaign -- First Constraints On Millimeter Flare Rates from ALMA